1. Field of the Invention
The present invention relates to a spring for centering two annular bodies, and specifically relates to such a spring as used in a rotary seal.
2. Description of the Related Art
Various applications require that two rotating rings be mounted concentrically to each other. In many cases, unequal thermal or centrifugal expansion between the two rings, due to material and/or structural differences, requires that the rings be concentrically mounted with a gap therebetween in order to account for the expansion. The prior art has attempted various methods for such mounting including links connecting the rings, sliding connections between the rings, and springs between the rings.
U.S. Pat. No. 5,039,113 discloses an example of a device requiring the mounting of two concentric rings. In this patent, a rotary seal ring is mounted within a rotary seal ring carrier. A finger spring, shown in FIG. 1 of this application, is located between the ring carrier and the seal ring to center the seal ring but leave a gap so that relative thermal and centrifugal expansion may occur without breakage of the seal ring. In-depth analysis of the finger spring disclosed in U.S. Pat. No. 5,039,113, has shown that the centering capability of the spring is limited to only a small portion of the estimated working range of spring deflection due to the effects of friction. It is therefore desirable to have an improved centering spring for use in such seals or other applications requiring the centering of two ring-shaped bodies, which for the purposes of this invention may include one solid annular body such as a shaft.